SANFORD, Fla. - George Zimmerman emerged from a Florida courthouse a free man after a jury cleared him of all charges in the fatal shooting of an unarmed Black teenager in a verdict that sparked largely peaceful protests across the country.

Zimmerman’s brother said the former neighborhood-watch volunteer was still processing the reality that he wouldn’t serve prison time for the killing of 17-year-old Trayvon Martin, which Zimmerman, 29, has maintained was an act of self-defense. A jury found him not guilty of second-degree murder late Saturday night and declined to convict him on a lesser charge of manslaughter.

However, with many critics angry over his acquittal, his freedom may be limited.

“He’s going to be looking over his shoulder the rest of his life,” Robert Zimmerman Jr. said during an interview on CNN.

Demonstrators upset with the verdict protested mostly peacefully in Florida, Milwaukee, Washington, D.C., Atlanta and elsewhere overnight and into the early morning Sunday, but some broke windows and vandalized a police squad car in Oakland during protests in four California cities, authorities said. Additional demonstrations were scheduled across the U.S. through Sunday evening, and one was held in the Valley.

The Rev. Jarrett Maupin held a rally Sunday evening at the Sandra Day O’Connor U.S. Courthouse in Phoenix for people to “express their anger and frustration” over the verdict. About 150 people attended.

“We are protesting the acquittal, the negative verdict,” Maupin said Sunday evening. “There is a lot of outrage and frustration in the African-American community. We have a young man who was racially profiled, we have a young man who was stalked, we have a young man who was hunted down.”

Maupin said he represents the Progressive Christian Coalition, which he said has members from the NAACP and the Greater Phoenix Urban League. Members of Occupy Phoenix were also expected to join the rally, Maupin said.

“This is a chance to grieve publicly and to see where we are going to go from here, to demand transparency and accountability,” Maupin said.

Amid the demonstrations, Benjamin Todd Jealous, president of the NAACP, started a petition calling for the U.S. Justice Department to open a civil-rights case against Zimmerman.

“The most fundamental of civil rights — the right to life — was violated the night George Zimmerman stalked and then took the life of Trayvon Martin,” Jealous wrote in the petition, posted on the website MoveOn.org and addressed to Attorney General Eric Holder.

In Washington, the Justice Department said it is looking into the case to determine whether federal prosecutors should file criminal civil-rights charges against Zimmerman.

In a Sunday afternoon statement, President Barack Obama called Martin’s death a tragedy for America but asked that Americans respect calls for calm reflection.

“I know this case has elicited strong passions,” he said. “And in the wake of the verdict, I know those passions may be running even higher. But we are a nation of laws, and a jury has spoken.”

The statement reflected the widespread national attention to the case. The White House rarely issues formal responses to trials that do not directly involve the president or federal government.

Martin’s killing in February 2012 unleashed debate across the U.S. over racial profiling, self-defense and equal justice. Protesters nationwide lashed out against police in the Orlando suburb of Sanford as it took 44 days for Zimmerman to be arrested. Many, including Martin’s parents, said Zimmerman had racially profiled the unarmed Black teen. Zimmerman identifies as Hispanic.

Six anonymous female jurors considered nearly three weeks of often wildly conflicting testimony over who was the aggressor on the rainy night the 17-year-old was shot while walking through the gated townhouse community where he was staying and where Zimmerman lived.

Jurors were sequestered during the trial, and they deliberated for more than 15 hours over two days before announcing late Saturday night that they had reached a verdict. The court did not release the racial and ethnic makeup of the jury.

In August 2012, defense attorney Mark O’Mara said Zimmerman and his wife, Shellie, had been living like hermits and weren’t working because they feared for their safety.

After Saturday’s verdict, police, officials and civil-rights leaders urged peace and told protesters not to resort to violence. While defense attorneys said they were thrilled with the outcome, O’Mara suggested Zimmerman’s safety would be an ongoing concern.

“There still is a fringe element that wants revenge,” O’Mara said. “They won’t listen to a verdict of not guilty.”

Those watching reacted strongly when the verdict was announced. Martin’s mother and father were not in the courtroom when it was read; supporters of his family who had gathered outside yelled, “No! No!” upon learning of the verdict.

Trayvon Martin’s brother, Jahvaris Fulton, said on Twitter: “Et tu America?” — a reference to the Latin phrase “Et tu, Brute?” known as an expression of betrayal referring to one of the conspirators who assassinated Julius Caesar.

In a statement Sunday, the Justice Department said the criminal section of its civil-rights division, the FBI and the U.S. Attorney’s Office for the Middle District of Florida are evaluating evidence to determine whether civil-rights charges should be filed against Zimmerman.

“Experienced federal prosecutors will determine whether the evidence reveals a prosecutable violation of any of the limited federal criminal civil rights statutes within our jurisdiction,” the statement said.

But experience has shown it’s almost never easy getting convictions in such high-profile prosecutions.

Alan Vinegrad, the former U.S. attorney in the Eastern District of New York, said the Justice Department “would face significant challenges in bringing a federal civil-rights case against Mr. Zimmerman.”

He said federal prosecutors “would have to show not only that the attack was unjustified, but that Mr. Zimmerman attacked Mr. Martin because of his race and because he was using a public facility, the street.”

Lauren Resnick, a former federal prosecutor in New York, said federal prosecutors were likely to encounter the same hurdles as state prosecutors in establishing that Zimmerman was driven by racial animus and was the initial aggressor, as opposed to someone who acted in self-defense.

Martin family attorney Benjamin Crump acknowledged the disappointment of Trayvon Martin’s supporters, ranking the teen alongside slain civil-rights heroes Medgar Evers and Emmett Till in the history of the fight for equal justice. However, Crump said, “for Trayvon to rest in peace, we must all be peaceful.”

Martin’s family maintained the teen was not the aggressor, and prosecutors suggested Martin was scared because he was being followed by a stranger. Defense attorneys, however, said Martin knocked Zimmerman down and was slamming the older man’s head against the concrete sidewalk when Zimmerman fired his gun.

Prosecutors called Zimmerman a liar and portrayed him as a “wannabe cop” vigilante who had grown frustrated by break-ins in his neighborhood committed primarily by young Black men. Zimmerman assumed Martin was up to no good and took the law into his own hands, prosecutors said.

State Attorney Angela Corey said after the verdict that she believed second-degree murder was the appropriate charge because Zimmerman’s mind-set “fit the bill of second-degree murder.”

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